Five randomly selected batches of a chemical were tested for impurity concentration. The percentage impurity levels found in this sample were as follows: XXXXXXXXXX a) Find the most efficient...

Five randomly selected batches of a chemical were tested for impurity concentration. The

percentage impurity levels found in this sample were as follows:
3 4 2 2 3
a) Find the most efficient estimates of the population mean and variance which are

sample mean and sample variance.
b) Find a 90% confidence interval for the population’s mean score.
c) Without doing the calculations, state whether a 95% confidence interval for the

population mean would be wider or narrower than the interval found in part b.